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Saliva Preservative for Diagnostic Purposes

Wednesday, 01 August 2012

This preservative can be used in remote areas without refrigeration for at least two months.

Saliva is an important body fluid for
diagnostic purposes. Glycoproteins, glucose,
steroids, DNA, and other molecules
of diagnostic value are found in saliva. It is
easier to collect as compared to blood or
urine. Un for tunately, saliva also contains
large numbers of bacteria that can release
enzymes, which can degrade proteins and
nucleic acids. These degradative enzymes
destroy or reduce saliva’s diagnostic value.
This innovation describes the formulation
of a chemical preservative that prevents
microbial growth and inactivates the
degradative enzymes. This extends the
time that saliva can be stored or transported
without losing its diagnostic value. Multiple
samples of saliva can be collected if
needed without causing discomfort to the
subject and it does not require any special
facilities to handle after it is collected.

The preservative contains sodium dodecyl
sulfate (SDS), ethylenediaminetetraacetic
acid (EDTA), and Tris buffer. This preservative
was developed to preserve saliva from
astronauts during spaceflight without refrigeration
to determine if virus DNA was present.
Saliva with added preservative can be
stored at room temperature for up to 60 days
without any measureable degradation. Viral
DNA is routinely measured from saliva stored
in this manner without refrigeration. Thus,
this preservative can be used to preserve critical
macromolecules (nucleic acids and proteins)
without consuming power resources.
This preservative has been used on flight
experiments aboard both the Space Shuttle
and the International Space Station.

Saliva contains hormones such as cortisol
and DHEA, cytokines (immune markers),
DNA and RNA viruses, antibodies, and
many other substances of diagnostic value.
Saliva also contains many bacteria that produce
proteases that destroy proteins, nucleases
that destroy DNA and RNA, and other
degradative enzymes. Typically, saliva and
other body fluids are refrigerated (or
frozen) to prevent or slow the degradation
process. Refrigeration and freezers are
extremely limited resources in spacecraft,
undeveloped countries, and during activities
away from electricity. Although not tested,
the preservative is expected to be effective
for other body fluids such as urine
and blood. In addition, the toxicity of
the preservative is very low.

The preservative consists of 0.5% sodium
dodecysulfate (a detergent), 1.0 mM EDTA
(a metal chelator), and 1.0 mM Tris (a
buffer to maintain correct pH). The preservative
is stable at room temperature for at
least six months. A small volume of the liquid
preservative is added to saliva (or other
body fluids), the mixture is mixed by inversion,
and then is left undisturbed at room
temperature until the analysis is conducted.
No other preservative has been identified
that stabilizes saliva and other body fluids at
room temperature for subsequent analyses.

This work was done by Duane L. Pierson of
Johnson Space Center and Satish K. Mehta of
EASI. MSC-25144-1

This Brief includes a Technical Support Package (TSP).

Saliva Preservative for Diagnostic Purposes (reference MSC-25144-1) is currently available for download from the TSP library.

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